1. Field of the Invention
The present invention relates generally to switch sensors, and more particularly, a transmission range switch with an internal shear pin design.
2. Background and Summary of the Invention
Transmission range switches contain switching circuits that are arranged to open and close in response to the driver's shift lever selection. The switching circuits perform independent electrical interlocking functions for starting, back-up lamps and various vehicle accessories. In addition, other circuits are independently arranged to open and close in unique combinations for each transmission gear range and provide a coded output to the vehicle. The transmission range switch references the manual shaft angular position with respect to the transmission case. The neutral/start switch portion of the sensor inhibits vehicle start in all selector ranges except neutral and park, and provides continuity to illuminate the back-up lamps in reverse only. The sensing portion of the sensor provides a signal to the vehicle identifying the transmission manual lever position.
It is necessary to maintain the transmission range switch in a predetermined position (for example neutral) during installation onto the transmission. Current methods of assuring that the range switch is maintained in a predetermined position during installation include the use of an external shear pin, a disposable alignment bracket or an alignment tool.
With the external shear pin, a shear pin is inserted through a hole in the outside of the switch and pressed into a hole in the carrier. The hole in the outside of the switch is sealed either with an O-ring or an adhesive. Retention of the shear pin is accomplished by heatstaking the housing and shear pin or by the adhesive.
With the disposable alignment bracket, a stamped metal part aligns features on the housing and carrier to hold the switch in neutral. Once the switch is installed on the transmission, the bracket is removed and discarded.
With the alignment tool, a tool or fixture at the assembly plant aligns features on the housing and carrier and maintains them in position until the installation is completed.
It is important that these switches are sealed against environmental moisture, dust and dirt for reliability and durability. The external shear pin method for aligning the carrier has potential leak paths through which external contamination could enter the switch. Further, the disposable alignment bracket method creates disposal problems with respect to the disposable bracket. In addition, the tool alignment method requires further assembly steps during installation.
Accordingly, it is an object of the present invention to provide a transmission switch sensor which supports the carrier in a predetermined position for installation and which eliminates potential leak paths for external contamination. The internal shear pin technique is self-contained with no additional assembly steps required during installation and nothing needs to be discarded.
These, and other objects of the present invention are obtained by providing a switch sensor including a housing having a switch circuitry disposed within the housing. An electrical contactor carrier is movably mounted within the housing. The electrical contactor carrier includes an opening therein and the housing includes a corresponding recess portion for receiving a shear pin therein wherein the shear pin is completely internal with respect to the switch sensor housing.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.